Conventional building construction has contemplated the sealing and containing of a fire source within a building. Fire doors of one to three hour ratings have been installed, walls were built to "compartmentalize" building sections with one to three hour ratings, to contain a fire in specific building components for predetermined periods of time. Roof and ceiling constructions were fire tested and evaluated in half hour to three hour containment criteria. The aim of such fire confinement is that the total consumption of the oxygen in the contained area will snuff out the fire.
With conventional fire containment philosophy, smoke and gases from partially burnt products and heat will reach a flash point. A spontaneous combustion explosion will occur when oxygen is introduced into a fire containment area, exposing smoke, gases, and entrapped heat thus spreading the fire rapidly throughout the total building from the fire entrapped area.
This invention is directed to precisely an opposite concept. This invention concerns the venting of heat, smoke and gases, hereafter collectively referred to as the combustion products of a fire, generated during fire within a building, directly out of the fire source. Such smoke, gases and heat build-up generated during a fire are the primary life threatening concerns, rather than the actual fire flames.
This invention accordingly seeks to ventilate fire as soon as detected, to vacate the heat, smoke and gases which are primarily responsible for loss of life. In addition, by venting a fire in a defined space, the consumable matter can be consumed by a fire in a building space and thus prevent build-up of smoke, gases and heat which will likely cause spontaneous spreading of fire throughout the building.
So-called smoke hatches are known to have been used in storage buildings with quantities of combustible or explosive materials, and in some instances, are required under uniform building code provisions. Most smoke hatches or vents are in the nature of a spring loaded door, hatch or skylight with a fusible link. Typically, heat or smoke vents are required in (a) single story buildings of non-hazardous use where the undivided floor area is over 50,000 square feet, (b) buildings as noted above with hazardous materials or uses when a single floor area exceeds 15,000 square feet, and (c) over stages larger than 500 square feet. While these are broad outlines of code requirements, such requirements vary from area to area.
Also, in recent years, automatic venting of building structures has been developed as an alternative and/or supplement to use of sprinkler systems to combat fires in commercial, industrial and residential buildings. In the event of fire, an automatic fire ventilator prevents buildup of gases which may create explosive conditions, as well as allowing heat and smoke to escape from a burning building Moreover, in buildings with extensive open or unpartitioned interiors, activated ventilators aid in locating the fire so it can be effectively fought from above while minimizing the need for cutting holes in the roof.
Several automatic fire venting devices have been developed and employed with success in conjunction with roofing structures. Examples of drop-out fire vents are shown in Nickerson U.S. Pat. No. 2,803,318 and Anghinetti et al U.S. Pat. No. 3,924,372. Additionally, Elmer U.S. Pat. No. 863,059 discloses a vent incorporating a fusible plug which, when heated, activates a sliding valve to release a closure and open the vent to atmosphere.
While fire vents, heat actuated skylights and trap doors have alleviated some of the above mentioned problems, they are capable of being inadvertently blown open by wind or other malfunctions due to mechanical specifications of the release mechanisms and usually do not provide a desired flexibility for different applications such as on roofing members or to effect desired venting of discrete levels of a multi-level building. Moreover, these conventional large metal vents, doors and acrylic skylights frequently introduce waterproofing and insulating problems in addition to normally requiring significant structural alterations to accommodate such units.